Do not call MemoryCache::prune() when a client/observer is removed

third_party/WebKit/Source/core/fetch/MemoryCache.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 630 matching lines @@
         while (true) {
             ResourceMap::iterator resourceIter = resources->begin();
             if (resourceIter == resources->end())
                 break;
             evict(resourceIter->value.get());
         }
         m_resourceMaps.remove(resourceMapIter);
     }
 }
 
-void MemoryCache::prune(Resource* justReleasedResource)
+void MemoryCache::prune()
 {
     TRACE_EVENT0("renderer", "MemoryCache::prune()");
 
     if (m_inPruneResources)
         return;
     if (m_liveSize + m_deadSize <= m_capacity && m_maxDeadCapacity && m_deadSize <= m_maxDeadCapacity) // Fast path.
         return;
 
     // To avoid burdening the current thread with repetitive pruning jobs,
     // pruning is postponed until the end of the current task. If it has
     // been more than m_maxPruneDeferralDelay since the last prune,
     // then we prune immediately.
     // If the current thread's run loop is not active, then pruning will happen
     // immediately only if it has been over m_maxPruneDeferralDelay
     // since the last prune.
     double currentTime = WTF::currentTime();
     if (m_prunePending) {
         if (currentTime - m_pruneTimeStamp >= m_maxPruneDeferralDelay) {
             pruneNow(currentTime, AutomaticPrune);
         }
     } else {
         if (currentTime - m_pruneTimeStamp >= m_maxPruneDeferralDelay) {
             pruneNow(currentTime, AutomaticPrune); // Delay exceeded, prune now.
         } else {
             // Defer.
             Platform::current()->currentThread()->addTaskObserver(this);
             m_prunePending = true;
         }
     }
-
-    if (m_prunePending && m_deadSize > m_maxDeferredPruneDeadCapacity && justReleasedResource) {
-        // The following eviction does not respect LRU order, but it can be done
-        // immediately in constant time, as opposed to pruneDeadResources, which
-        // we would rather defer because it is O(N), which would make tear-down of N
-        // objects O(N^2) if we pruned immediately. This immediate eviction is a
-        // safeguard against runaway memory consumption by dead resources
-        // while a prune is pending.
-        if (MemoryCacheEntry* entry = getEntryForResource(justReleasedResource))
-            evict(entry);
-
-        // As a last resort, prune immediately
-        if (m_deadSize > m_maxDeferredPruneDeadCapacity)
-            pruneNow(currentTime, AutomaticPrune);
-    }
 }
 
 void MemoryCache::willProcessTask()
 {
 }
 
 void MemoryCache::didProcessTask()
 {
     // Perform deferred pruning
     DCHECK(m_prunePending);
@@ skipping 61 matching lines @@
 bool MemoryCache::isInSameLRUListForTest(const Resource* x, const Resource* y)
 {
     MemoryCacheEntry* ex = getEntryForResource(x);
     MemoryCacheEntry* ey = getEntryForResource(y);
     DCHECK(ex);
     DCHECK(ey);
     return lruListFor(ex->m_accessCount, x->size()) == lruListFor(ey->m_accessCount, y->size());
 }
 
 } // namespace blink